Ultraconserved words point to deep language ancestry across Eurasia.

The search for ever deeper relationships among the World's languages is bedeviled by the fact that most words evolve too rapidly to preserve evidence of their ancestry beyond 5,000 to 9,000 y. On the other hand, quantitative modeling indicates that some "ultraconserved" words exist that might be used to find evidence for deep linguistic relationships beyond that time barrier. Here we use a statistical model, which takes into account the frequency with which words are used in common everyday speech, to predict the existence of a set of such highly conserved words among seven language families of Eurasia postulated to form a linguistic superfamily that evolved from a common ancestor around 15,000 y ago. We derive a dated phylogenetic tree of this proposed superfamily with a time-depth of ~14,450 y, implying that some frequently used words have been retained in related forms since the end of the last ice age. Words used more than once per 1,000 in everyday speech were 7- to 10-times more likely to show deep ancestry on this tree. Our results suggest a remarkable fidelity in the transmission of some words and give theoretical justification to the search for features of language that might be preserved across wide spans of time and geography.

Feasibility of selective nanoparticle-assisted photothermal treatment for an embedded liver tumor.

Using the finite volume method, the present work numerically explored the feasibility of extending nanoparticle-assisted photothermal therapy (PPTT) from treating subcutaneous tumors to treating organ tumors, particularly tumors growing in the clearance organ liver. To serve this purpose, a superficially embedded liver tumor and its immediate surrounding medium were selected as the study object. A 633-nm laser beam of 1- W/cm(2) intensity externally irradiated the tumor. The matching gold-silica nanoshell with a 16-nm silica core and a 5-nm-thick gold shell was used as the photothermal agent. The nanoshell retention ratio was varied to simulate different levels of nanoshell tumor discriminations. Laser light distributions, conversions from photon energy to heat, and tissues' thermal responses to the generated heat within the study object were analyzed. It was found that although nanoshells have enhanced the thermal transportation, they also restricted the optical transportation of PPTT. This indicates that laser delivery is more demanding for PPTT than for the conventional laser therapy. For the investigated case, when the nanoshell retention ratio was in the range of 2/1-4/1, the therapeutic effects were optimal: a confined medium temperature hyperthermia (47-55 °C) was achieved in the liver tumor while impacts on the surrounding health liver tissues were only marginal. When then nanoshell retention ratio was 8/1 or higher, about half of the liver tumor was ablated. However, some of the surrounding healthy liver tissues were sacrificed as well. The therapeutic effects of PPTT depend nonlinearly on the nanoshell tumor discriminations. Better tumor discriminations do not necessarily result in better PPTT therapeutic effects.

Numerical investigation of nanoparticle-assisted laser-induced interstitial thermotherapy toward tumor and cancer treatments.

In this work, we numerically investigated nanoparticle-assisted laser-induced interstitial thermotherapy for tumor/cancer treatments. The goal of the study was to investigate the therapeutic effects of treatment conditions including laser wavelength, power, exposure time, concentrations of tailored nanoparticles, and optical/thermal properties of the tissue that is under treatment. It was found that using absorbing preferential nanoparticles as the photothermal agent weakens fluence rate distributions in terms of lowering fluence rate peaks and reducing laser penetration depths. However, the local enhancement in laser photon absorption induced by nanoparticles is so significant that the reduced fluence rate will be balanced out, and the eventual medical hyperthermia is greatly prompted by using nanoparticles. Also, the results of numerical simulations indicated that with constant laser illumination, an increase in nanoparticle concentration beyond a certain range has only an insignificant impact on hyperthermia.